A prior art method of scalable DCT-based image compression is disclosed in International Patent Application WO2005/112467. The method is envisaged for use in wireless transmission of High Definition television signals, also referred to as WirelessHD, in particular for the purpose of invisibly connecting a wall-mounted HDTV flat screen monitor to an external HDTV signal source.
In experimental evaluations of the prior art compression method in the context of WirelessHD, the inventors found that an improvement of the compression performance was desired for certain computer-graphics content. For WirelessHD, both natural image content and graphics content should be supported, but the method prior art was designed for compression of natural image content and not optimized specifically for graphics content.